Risk – Illness and Disease
I am sorry that there have not been very many blog postings of late. Inevitably starting a new blog and having newborn twins at the same time was going to create a clash of time – so welcome back those of you that hung in there – I plan to be posting more regularly in the future.
I’d like to write today about RISK ….
This might seem to be a strange subject – but in fact understanding risk – in particular understanding the risk of illness and disease – is vital to our understanding of how best to look after ourselves. It is also essential that we understand the chances of benefit versus harm – before we accept treatment.
We need to be able to convert potentially confusing statistics into something that makes sense in real life terms before we can truly be making informed decisions about our health.
Without wishing to be in any way disparaging, it is also quite clear that most of the medical profession struggle with this too – in one research paper 75% of GPs admitted that they did not understand how drug companies presented statistics in scientific journals.
You will see from elsewhere on this website that my views on the pharmaceutical industry are somewhat jaded. I’m very much aware, as indeed are many other people, that Big Pharma is very keen to distort the way they present research so that the risks of various illnesses may appear far greater than they really are and the amount of benefit of treatment may appear far greater than it actually is…. Never has the saying “lies, damn lies and statistics” been more true.
There are a number of concerns with our management of risk….
Treating the Wrong Risk Factor
“God, grant me the serenity to accept the things I cannot change, The courage to change the things I can, And the wisdom to know the difference.” Reinhold Neibur.
I have chosen the subject of risk because of a number of recent patient incidents around the prescribing of statins. These cases nicely illustrate my concerns around the confusing state of medical guidelines and research.
Those of you that keep up-to-date with medical news may have noticed a few months ago that there was a significant debate about whether more people should be offered statins. Despite protests from a considerable proportion of the medical profession, NICE decided that we should offer statins to anyone who is at a 10% or greater risk of developing heart disease in the next 10 years i.e. if you have a 1/10 chance over the next 10 years then you should be offered a statin. (The previous guidance was 20% i.e. 1 in 5).
Now there is a fundamental problem here… the risk of developing heart disease is dependent on a whole host of factors and not simply cholesterol – there is considerable evidence to show it has nothing to do with cholesterol at all but that is not (yet) mainstream thinking and I will leave this to another blog post -these risk factors include smoking, being poor, high blood pressure and age amongst other things.
Two cases illustrate the confusion this creates…
Recently I was asked to give advice on a lady of 70 who had had blood tests done showing a cholesterol profile that was actually very reasonable –in fact as good as it gets, while accepting all the limitations on what your cholesterol levels actually mean.
Now on our GP systems there is a clever piece of software called QRISK that runs a calculation on your heart disease risk allowing for blood pressure, age, smoking, family history and cholesterol etc. This lady’s calculation showed she had a risk of 10.5% over the next 10 years of developing heart disease and she was duly requested to speak to a doctor with a view to going on statins to lower her cholesterol.
BUT the important point, that was lost in the obsession with the 10% figure, was that she was actually running a risk just over half that of the average women of her age – i.e. just being 70, with all else being equal, gives you a 20% risk. So unless statins magically make you younger why on earth would we consider giving a statin to someone whose risk is in fact far less than we would expect for her age?
A similar tale applies to a family member of mine whose blood pressure during a hospital appointment was found to be higher than ideal – high blood pressure increases your QRISK score and low and behold they were offered a statin as now their risk was higher. Given that statins lower cholesterol but don’t treat blood pressure I remain baffled by this approach.
So we clearly have the danger of an illogical approach to what we can and cannot alter with respect to risk and the inherent danger of trying to treat the wrong thing but there is more to this issue than this….
Relative Risk versus Absolute Risk
This is extremely rich territory for the distortion of risk and benefit – let’s quote another statin example.
One of the commonest trials used to justify the use of statins to prevent heart disease is the JUPITER trial. This trial is riddled with inconsistencies, was sponsored and monitored by AstraZenaca (who patented the drug used in the trial) and was stopped early for dubious reasons, but putting aside these considerations let’s look at how the data from the trial was presented….
The authors boasted that statin drugs could lower:
- the risk of heart attack by 54 percent
- the risk of stroke by 48 percent
- the risk of needing angioplasty or bypass surgery by 46 percent
- and the risk of death from all causes by 20 percent.
(These are called “endpoints” in scientific studies and there was already a question mark as the use of angioplasty or surgery is medical treatment decision not a clearly defined disease event or death.)
This 54% reduction certainly appears impressive and indeed was promoted to health professionals and the public alike. BUT let’s look at the actual figures…
There were 17,802 people in the study and there was a difference in endpoint rate of 2.8% in the placebo group vs 1.6% in the treatment group.
The benefit with regards to the number of fatal and nonfatal heart attacks was even smaller. There were only 68 (0.76%) vs 31 (0.35%) events respectively. The difference between the two was 37 events (0.41%)
SO… if we look at what this data means –
RELATIVE RISK REDUCTION was calculated (and boasted about) as 54% – because 0.41 is 54% of 0.78
ABSOLUTE RISK REDUCTION is actually the 0.41%
So on the one hand the drug company claimed a 54% reduction in heart disease but in actual number terms the reduction was 0.41% – this is a staggering difference and undoubtedly distorts the way treatment is offered by doctors and accepted by patients.
If looking at these figures has left you baffled then the point to remember is that if something only happens very rarely than a large relative risk change will only mean a very small absolute risk change in the real world.
One way I often describe this to patients is that if I advise them to buy two lottery tickets instead of one then they have a 100% increased chance of winning! This clearly is meaningless as the chance has only increased from 1 in 14 million to 1 in 7 million – the absolute percentage chance increase is so tiny my calculator won’t even show it in a meaningful way!!
Numbers Needed to Treat (NNT) and Delay of Harmful Event
There are alternative ways at looking at risk and benefit that are more in tune with real life thinking rather than arcane calculations.
One of these is the NNT – this calculates then number of people who need to take a treatment for one person to benefit. If we consider the JUPITER study again then remember that the vast majority of people did not develop heart disease whether they were on treatment or not. On top of this a number of people on treatment developed heart disease despite being on it, so again being on treatment made no difference to them. The actual NNT to prevent heart disease was 244.
Yes…..244 people needed to be treated to prevent a single fatal or nonfatal heart attack!
(For the nerds among you the figure of NNT comes from the 0.41% absolute risk reduction – 0.41/100 =243.9)
As an aside, we also need to consider the Number Needed to Harm (NNH) – very few treatments come without potential harm and statins have a multitude of harmful effects. The NNH to cause muscle damage is at most 10 and probably closer to 2-3. The NNH to cause diabetes is somewhere between 50 and 100. You can see from this that the chance of harm considerably outweigh the chances of benefit.
There is an even more meaningful way to consider benefit and that is to consider how long you delay an illness or death by taking a treatment. I am indebted to Dr Malcolm Kendrick, the author of The Great Cholesterol Con (aff-link) do check him out!, for pointing out that although much of medical research talks about lives saved there are actually no immortals walking among us (unless of course some of the Swamis in India are to be believed!) In other words you cannot actually “save a life” you can only delay death.
Conveniently a recent research paper in the British Medical Journal has answered this question for statins by looking at a number of the statin trials and calculating the life extension. You will work out for yourself why they had to do the calculations and they were not already done and reported for each of the studies by the original researchers.
For secondary prevention (i.e. people who have already developed heart disease and therefore at the highest risk) taking a statin showed an average delay of death of just 4.1 days (range – 10 to +27 days) – this can be translated as extending life by just over one day for every year taking a statin.
For primary prevention (people who have not had heart disease) the average postponement of death was merely 3.2 days (range -5 to +19 days). This indicates an extension of life by a bit less than one day for every year taking a statin.
So there you have it “caveat empor” or to use English rather than Latin – “buyer beware!”
Do ask the right questions, don’t be afraid to challenge and …..
Take care of you!
Dr David Morris
Family Practitioner and Integrative Medicine Physician